At $4.5 billion, the agreement announced Thursday to settle federal criminal charges against BP for the 2010 oil spill ranks as one of the biggest penalties in U.S. history.

The majority of that money goes to a group of federal agencies that in turn could send it back to the Gulf Coast, with Louisiana positioned to be the biggest beneficiary. When, where and how the money gets distributed remains to be seen, but experts say it's just an initial payment on the total amount owed by BP for its role in the catastrophe.

The bigger money could come in civil penalties BP faces for violations of the federal Clean Water Act and Oil Pollution Act, with estimates ranging from $5.4 billion to $22 billion. The difference depends on whether BP is guilty of simple negligence - at a fine of $1,000 for every barrel of oil spilled - or grossly negligent, which carries a fine of $4,300 per barrel.

It's that money that would flow to the Gulf Coast via the Restore Act, federal legislation approved by Congress and signed by President Barack Obama in July. U.S. Attorney General Eric Holder said the government is in negotiation with BP to resolve the civil claims, with a trial set for February in New Orleans.

"We have not reached a number that I consider satisfactory," Holder said Thursday at a news conference in New Orleans.

Thursday's $4.5 billion deal breaks down as follows:

$2.4 billion to the National Fish and Wildlife Foundation, which said it will use the money for environmental remediation on the Gulf Coast

$1.3 billion in criminal fines, which could go to the U.S. Coast Guard's Oil Spill Liability Trust Fund

$525 million to the Securities and Exchange Commission to settle criminal charges that BP misled investors

$350 million to the National Academy of Sciences, which said it will use the money to establish a new, 30-year program on human health and environmental protection in the Gulf of Mexico.

How that money gets divided among the states remains uncertain, and much of it will be paid out by BP over the next three to five years.

"I don't know how the criminal settlement affects us," said Gulf Shores Mayor Robert Craft. "I'm trying to get my arms around this and find out where the money is going."

Others said Louisiana, which suffered the brunt of environmental damage from the spill, should receive the biggest share of proceeds from the criminal penalties.

The Times-Picayune newspaper of New Orleans reported Thursday that the settlement is likely to prove a boon for Louisiana, with $1.2 billion out of the fines to be used to restore barrier islands and to build a Mississippi River freshwater and sediment diversion.